This application claims the priority of German Patent Document 101 54 926.1, filed on Nov. 8, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a coolant circuit for an internal combustion engine, with a coolant radiator, at least one mechanical coolant pump and at least one electrical coolant pump for a cooling circuit having a coolant inflow and for a heating circuit having a coolant return, in each case with at least one heat exchanger, the mechanical coolant pump and/or the electrical coolant pump being assigned to the heating and/or cooling circuit, and the mechanical pump being capable of being cut in and cut out or of being throttled.
A coolant circuit for an internal combustion engine of motor vehicles is already known from DE 195 06 935 C1, which has a heating circuit independent of the engine cooling circuit and provided with an electrical pump device. The pump device is capable of being cut in and out in a rotational-speed-regulated and/or timed manner by an electronic control or regulating device for controlling or regulating the heating capacity of the heating circuit. In this case, a coolant inflow and a return of the heating circuit are integrated in a common connection piece arranged directly on an engine block of the internal combustion engine.
An aspect on which certain preferred embodiments of the invention are based is to design and arrange a coolant circuit in such a way as to ensure optimum heat utilization in conjunction with a fuel saving.
This aspect is achieved in that the mechanical coolant pump and/or electrical coolant pump is assigned to the heating and/or cooling circuit and/or the mechanical pump is capable of being cut in and cut out, thereby achieving that the electrical coolant pump can be used alternatively or additionally, depending on the rotational speed of the engine or of the mechanical coolant pump and according to the demand for waste heat within the cooling circuit or the heating circuit. It is also possible for the electrical coolant pump, as an alternative to the mechanical coolant pump, to ensure both the cooling circuit and the heating circuit. This ensures optimum heating of the internal combustion engine, a supply of heat to the passenger cell which is independent of the engine rotational speed, and also an associated fuel saving.
For this purpose, it is advantageous that the coolant return of the heating circuit is throughflow-connected to the coolant inflow of the cooling circuit and the coolant circuit can be separated from the coolant radiator, or a coolant shunt circuit separate from the coolant radiator is provided between the internal combustion engine, the cooling circuit and/or the heating circuit. The two coolant streams can thus be brought together, it being possible to discharge the waste heat from the cooling circuit to the heating circuit when the coolant radiator is separated from the coolant circuit.
Furthermore, it is advantageous that the cooling circuit is throughflow-connected to the heat exchanger, designed as an oil cooler, to the internal combustion engine and/or to the heating circuit, and the heating circuit is throughflow-connected to the heating heat exchanger, to the internal combustion engine and/or to the cooling circuit. This allows the greatest possible heat compensation between the cooling circuit and the heating circuit.
It is also advantageous, for this purpose, that a throttle circuit, separate from the coolant circuit or from the coolant shunt circuit, is provided between the electrical or the mechanical coolant pump, the internal combustion engine and a controllable or regulatable throttle. Where high throttling resistance is concerned, the cooling circuit may also be ensured via the electrical coolant pump and, where a low throttling resistance is concerned, the heating circuit can also be ensured via the electrical coolant pump. Both coolant circuits are thus operatively connected to both coolant pumps.
Finally, according to a preferred embodiment, it is provided that the cooling circuit of the internal combustion engine is throughflow-connected to the coolant radiator, designed as an air radiator, and/or to the heating circuit via the mechanical coolant pump and/or the electrical coolant pump, and that the mechanical coolant pump, the electrical coolant pump, the air radiator, the heating heat exchanger and/or the oil cooler are capable of being cut into and cut out from the coolant circuit or of being throttled via a valve.
With regard to the design and arrangement, it is advantageous that the valve has at least one coolant inflow and at least one coolant outflow capable of being cut in and out or of being throttled, and the valve is assigned a temperature-dependent and/or regulatable control member, such as a thermostat and/or a controller.
It is advantageous, furthermore, that the internal combustion engine has at least one coolant inflow throughflow-connected to the mechanical coolant pump and at least one coolant inflow throughflow-connected to the electrical coolant pump and at least one coolant return throughflow-connected to the throttle, to the second heat exchanger of the heating circuit and to the first heat exchanger of the cooling circuit.
It is advantageous, moreover, that the throttle is assigned an actuating and/or regulating member, at least one coolant outflow of the oil cooler, at least one coolant outflow of the heating heat exchanger, at least one coolant outflow of the internal combustion engine and/or at least one coolant outlet of the air radiator having a temperature sensor.
The functional features of the valves, their arrangement and the use of the temperature sensors ensure that a control and regulating device is employed for the optimum utilization of the existing and useful heat quantities.